These days, medical 3D image records are predominantly evaluated using visually displayed 2D slice images which are generated on the basis of the recorded 3D image data. This practice is also applied if the structures to be analyzed in the 3D image records have a tubular geometry. Examples of tubular structures include tubular hollow organs, such as the colon, or vessels, such as e.g. the aorta or the coronary vessels. In the latter cases, the evaluation of the tubular structures is particularly focused on analyzing pathological changes, usually on the inner walls of the tubular structure. A stenotic region in a vessel section is mentioned here in an exemplary manner. From a medical point of view, it is the goal in this case to find out to what extent the narrowed region influences the overall medical function of the vessel section. In the present example of narrowing of vessels, this means that the medical practitioner analyzes the 3D image records to determine whether enough blood can still flow through the vessel, despite the narrowing of the vessel, so that e.g. the myocardium still has a sufficient supply of oxygen.
For the evaluation of tubular structures, the prior art discloses the determination of a centerline in the recorded 3D image data, which centerline represents the three-dimensional tubular structure imaged in the 3D image data. To this end, the prior art uses known skeletonizing or thinning methods. Here, this centerline is used as a path for the visualization using 2D slice images. This means that for a point of the centerline which can be selected manually (every image voxel belonging to the centerline), one 2D cross section of the tubular structure, which is orthogonal to the centerline at the selected point, and two 2D slice images with tangential sectional planes are generally calculated and displayed visually. Usually, all three planes are orthogonal to one another. By repeatedly selecting points of the centerline, corresponding 2D slice images, respectively containing the selected point, are generated and displayed. Particularly when continuously selecting adjacent points of the centerline, corresponding to, for example, continuous motion back and forth along the path, the tubular structure can be evaluated using the 2D slice images respectively displayed in the process.
However, the problem with this procedure is that, particularly in the case of strongly curved tubular structures or else in the case of tubular structures whose curvature changes weakly but frequently, the described 2D slice images (tangential planes) “jump” very strongly from image to image when “continuously passing over the path”. Hence, the display profile when continuously passing over the structure is very jittery; this requires the increased attention of the evaluating medical practitioner and increases the risk of misinterpretation of the displayed 2D slice images.